Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Em qual pesquisa Nathan Deal está com 13% e John Oxendine com 28%?
 ###Tabelas: CREATE TABLE republican_primary (republican_primary_id AUTO_INCREMENT PRIMARY KEY, Poll source VARCHAR, Dates administered VARCHAR, John Oxendine VARCHAR, Karen Handel VARCHAR, Nathan Deal VARCHAR, Eric Johnson VARCHAR, Ray McBerry VARCHAR, Undecided VARCHAR) CREATE TABLE 2011_supertwin_practice_times_and_leaderboard (2011_supertwin_practice_times_and_leaderboard_id AUTO_INCREMENT PRIMARY KEY, Rank INT, Rider VARCHAR, Sat 20 Aug VARCHAR, Mon 22 Aug VARCHAR, Tues 23 Aug VARCHAR, Wed 24 Aug VARCHAR, Thurs 25 Aug VARCHAR, Fri 26 Aug VARCHAR) CREATE TABLE skilift_system (skilift_system_id AUTO_INCREMENT PRIMARY KEY, Name or route VARCHAR, type VARCHAR, elevation groundstation INT, elevation mountainstation INT, slope length INT, capacity in persons/hour INT, construction year(s) VARCHAR) CREATE TABLE area_and_population (area_and_population_id AUTO_INCREMENT PRIMARY KEY, Member State VARCHAR, Population in millions VARCHAR, Population % of EU VARCHAR, Area km 2 INT, Area % of EU VARCHAR, Pop. density People/km 2 VARCHAR) CREATE TABLE formula_3_results_summary (formula_3_results_summary_id AUTO_INCREMENT PRIMARY KEY, Season INT, Series VARCHAR, Points VARCHAR, Position VARCHAR, Driver VARCHAR)  
SELECT Poll source FROM republican_primary WHERE Nathan Deal = 13% AND John Oxendine = 28%